Temporary stabilization with capital controls

Exchange rate based stabilization, Capital controls, F32, F41,

Direct Comparison of the Spread Area, Contractility, and Migration of balb/c 3T3 Fibroblasts Adhered to Fibronectin- and RGD-Modified Substrata

Native proteins are often substituted by short peptide sequences. These peptides can recapitulate key, but not all biofunctional properties of the native proteins. Here, we quantify the similarities and differences in spread area, contractile activity, and migration speed for balb/c 3T3 fibroblasts adhered to fibronectin- (FN) and Arg-Gly-Asp (RGD)-modified substrata of varying surface density. In both cases spread area has a biphasic dependence on surface ligand density (σ) with a maximum at σ ∼ 200 molecules/μm(2), whereas the total traction force increases and reaches a plateau as a function of σ. In addition to these qualitative similarities, there are significant quantitative differences between fibroblasts adhered to FN and RGD. For example, fibroblasts on FN have a spread area that is on average greater by ∼200 μm(2) over a ∼40-fold change in σ. In addition, fibroblasts on FN exert ∼3–5 times more total force, which reaches a maximum at a value of σ ∼5 times less than for cells adhered to RGD. The data also indicate that the differences in traction are not simply a function of the degree of spreading. In fact, fibroblasts on FN (σ ∼2000 μm(−2)) and RGD (σ ∼ 200 μm(−2)) have both similar spread area (∼600 μm(2)) and migration speed (∼11 μm/h), yet the total force production is five times higher on FN than RGD (∼0.05 dyn compared to ∼0.01 dyn). Thus, the specific interactions between fibroblasts and FN molecules must inherently allow for higher traction force generation in comparison to the interactions between fibroblasts and RGD